linux/scripts/mod
Masahiro Yamada d0acc76a49 modpost: remove broken calculation of exception_table_entry size
find_extable_entry_size() is completely broken. It has awesome comments
about how to calculate sizeof(struct exception_table_entry).

It was based on these assumptions:

  - struct exception_table_entry has two fields
  - both of the fields have the same size

Then, we came up with this equation:

  (offset of the second field) * 2 == (size of struct)

It was true for all architectures when commit 52dc0595d5 ("modpost:
handle relocations mismatch in __ex_table.") was applied.

Our mathematics broke when commit 548acf1923 ("x86/mm: Expand the
exception table logic to allow new handling options") introduced the
third field.

Now, the definition of exception_table_entry is highly arch-dependent.

For x86, sizeof(struct exception_table_entry) is apparently 12, but
find_extable_entry_size() sets extable_entry_size to 8.

I could fix it, but I do not see much value in this code.

extable_entry_size is used just for selecting a slightly different
error message.

If the first field ("insn") references to a non-executable section,

    The relocation at %s+0x%lx references
    section "%s" which is not executable, IOW
    it is not possible for the kernel to fault
    at that address.  Something is seriously wrong
    and should be fixed.

If the second field ("fixup") references to a non-executable section,

    The relocation at %s+0x%lx references
    section "%s" which is not executable, IOW
    the kernel will fault if it ever tries to
    jump to it.  Something is seriously wrong
    and should be fixed.

Merge the two error messages rather than adding even more complexity.

Change fatal() to error() to make it continue running and catch more
possible errors.

Fixes: 548acf1923 ("x86/mm: Expand the exception table logic to allow new handling options")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-05-22 10:34:38 +09:00
..
.gitignore .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
devicetable-offsets.c cdx: add the cdx bus driver 2023-03-29 12:26:32 +02:00
empty.c
file2alias.c cdx: add the cdx bus driver 2023-03-29 12:26:32 +02:00
list.h modpost: import include/linux/list.h 2022-05-08 03:17:00 +09:00
Makefile scripts/mod: disable LTO for empty.c 2021-01-14 08:21:09 -08:00
mk_elfconfig.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
modpost.c modpost: remove broken calculation of exception_table_entry size 2023-05-22 10:34:38 +09:00
modpost.h modpost: refactor get_secindex() 2022-08-03 22:56:46 +09:00
sumversion.c modpost: fix array_size.cocci warning 2022-11-21 10:18:39 +09:00